1. Field of the Invention
The present invention relates to a device for electrostimulation of the eye, comprising a spectacles-like supporting frame which has a nose part and an arrangement, connected to the nose part, for holding the supporting frame on the head of the patient, wherein at least one stimulation electrode is arranged on the nose part.
2. Related Prior Art
Such a device has been disclosed in US 2004/0176820 A1, now issued as U.S. Pat. No. 7,158,834.
The known device and further devices from the prior art are used to route electric stimulation signals into the eye because it was found that specific forms of macular degeneration and other eye disorders can be stabilized and even improved as a result of this.
Retinal degeneration is a significant cause of blindness in industrialized countries. Various studies provide indications that low electrical currents which flow through the retina can delay the onset of hereditary, age-related or sudden degeneration of the retina.
This opens up the possibility of being able to delay the gradual loss of sight by means of regular, that is to say, e.g., daily or weekly, electric stimulation of the eye in order thus to maintain parts of the vision for longer in affected patients, or even restore parts of the vision.
Expediently, this treatment should be carried out by the patient himself and at home. In doing so, in the extreme case, the assumption must be made that the patient is practically blind. This results in significant demands on the device mentioned at the outset.
The device known from US 2004/0176820 A1, now issued as U.S. Pat. No. 7,158,834, mentioned at the outset, is a type of spectacles with a nose part covering both eyes in the style of a diving mask, with a plurality of electrodes arranged thereon which establish contact with the eye when the spectacles are put on.
To this end, the known spectacles are equipped with a type of elastic band, by means of which the spectacles in the style of a diving mask put on by the patient are held against the head such that they rest tightly against the face around the region of the eye.
A plurality of electrodes are provided around the area of the eye and these establish a punctiform contact to the tissue immediately surrounding the eyes.
It is mentioned that it is also possible to use an individual electrode, which can rest against the closed eyelid or against any other eye tissue.
The electrodes are connected—this is not explained in more detail—to a stimulation instrument which generates electric signals that are routed via the electrodes into the eyes as stimulation signals. The required counter electrode is attached anywhere on the body of the patient.
The inventor of US 2004/0176820 A1, now issued as U.S. Pat. No. 7,158,834, reports that various forms of retinal degeneration can be halted, with the state of the patient sometimes even improving again, through use of the known spectacles when stimulation signals of specific frequencies, currents and voltage ranges are applied.
A similar approach is adopted by the device described in PCT Patent Publication No. WO 2005/077452 A1, which likewise makes possible the electrostimulation of the eye.
In this device, the electrodes are embodied in the form of foam pads which are placed onto the closed eyelids. The counter electrode is connected to the hand of the patient.
A stimulation instrument is also connected to the electrodes in this case in order to route electric stimulation signals into the eyes.
U.S. Pat. No. 5,522,864 A also describes the use of a foam electrode, to be placed onto the closed eyelid, for electrostimulation on the eye, with the electrode and, optionally, parts of the stimulation electronics being attached to the head of the patient by a headband.
U.S. Pat. No. 6,035,236 A and U.S. Pat. No. 6,275,735 B1 describe methods for electrostimulation, in which stimulation signals are applied to specific stimulation points on the skin around the eye.
European Patent Application No. EP 0 325 201 A2, now abandoned, describes a stimulation instrument for improving vision, which comprises a spectacles-like supporting frame, on which a sprung element is arranged, which presses a plate against the closed eyelid. Provided on the plate there is an areal electrode, which lies on the closed eyelid and emits stimulation signals.
The issued patent DE 90 11 254 U describes therapeutic spectacles for electrical stimulation of specific areas of skin around the eye. Electrode plates have been introduced into the spectacles and these come into direct contact with the areas of skin to be stimulated when the spectacles are put on.
A disadvantage of all devices described insofar is that the electric stimulation of the eye is brought about by electrodes placed onto the skin, as also already known from other fields of application of electrostimulation.
Thus, electrostimulation in general was already proposed as early as the 18th century for the treatment of very different clinical pictures, including eye disorders as well. Very different embodiments for the utilized electrodes were proposed in the process.
One embodiment option consists of looking with opened eyes into a water bath consisting of physiological saline, wherein the water bath contains electrodes that are connected to the stimulation instrument. This method is called iontophoresis. However, due to the difficulties associated therewith, iontophoresis has not found widespread use.
Electrodes applied to the eyes are also used in electroretinography (ERG). In this ophthalmological diagnosis method, electrodes are attached in the vicinity of the eye, flashes of light are guided into the eye and the corresponding nerve currents through the optical nerve are measured at the electrodes.
Within the scope of applying ERG, it was found that there are large variations in the signal amplitude if use is made of electrodes applied to the skin and that the signal amplitude depends on the current state of the skin, i.e., on the fat content thereof, on the moisture thereof and, for example, the fact whether it was recently washed.
These effects are not very bothersome for ERG because the electrodes in this case are used to conduct away measurement currents where the time profile of the signals is of interest.
However, these effects are unacceptable for the therapeutic application planned within the scope of the present application. This is because if the skin resistance is very different from application to application, it proves impossible to ensure that the electric field strength generated on the retina is reproducible and that therapeutic success can be expected.
Furthermore, in order to avoid these effects, electrodes are preferably also used in ERG which establishes direct contact with moist body surfaces, which is of low resistance. Therefore, in ophthalmology, the stimulation electrode generally contacts the cornea, i.e., the eye surface. A large area counter electrode is then applied to the skin, the large area of which ensures a low contact resistance and hence reproducible conditions.
Eye electrodes known from ERG first of all include metallically coated contact lenses, as are used in U.S. Pat. No. 7,020,527 for electrostimulation. These contact lenses are considered to be difficult to tolerate and painful because the curvature thereof is not precisely fitted to the eye for reasons of costs.
U.S. Pat. No. 5,154,174 A has disclosed the use of bent wire loops as electrodes for ERG, which are inserted into the conjunctival sac of the eye. These electrodes, which are also known as Hawlina electrodes, are significantly more tolerable than the metallically coated contact lenses, but are difficult to handle for blind patients because they cannot monitor the precise shape and the seat of the wire loop. Adhesive plasters are generally used for fixation to the head, which is disadvantageous in that the position of the electrode can change over the whole duration of the stimulation.
So-called DTL electrodes, as offered by Diagnosys LLC, Lowell, Mass., USA, have also found widespread use in ERG.
These DTL electrodes consist of a fine wire, which is placed onto the cornea such that it lies on the eyelid/cornea edge and has good contact to the cornea. The wire is attached with plasters to the left and right of the treated eye.
These electrodes have been tested many times in ERG, they are the most tolerable of all the known ERG electrodes, but are disadvantageous in that the medical practitioner or orderly requires great manual dexterity for the application thereof in clinical practice. A patient generally does not have this ability, particularly if the patient is blind. Hence these electrodes cannot be applied independently by patients.